Research Document - 2000/09
Assessments of Atlantic salmon stocks of Salmon Fishing Areas 20 and 21, the southern Upland of Nova Scotia, for 1999.
By Amiro, P.G., Longard, D.A., Jefferson, E.M.
Abstract
Assessment of the Atlantic salmon (Salmo salar) stocks of two Salmon Fishing Areas, SFA 20 on the Eastern Shore and SFA 21 on the Southern shore of Nova Scotia indicated that returns in 1999 were insufficient to achieve conservation requirement in any index river. Returns to low-acidified index rivers were only 22% of the adult salmon requirement in the St. Marys River and 48% of the requirement for the area above Morgans Falls on the LaHave River. Generation-to-generation survival above Morgans Falls for the 1994 egg deposition year-class was again below replacement. Smolt to one-sea-winter survival of stocked hatchery smolts continued a declining trend since 1984 to 0.31% while survival to two-sea-winter salmon increased marginally to 0.17%. Wild smolt survival back to Morgans Falls decreased to 2.04%. The ratio of wild to hatchery returns for one-sea-winter salmon was 4.8, 5.0 and 6.6 for the 1996 to 1998 smolt classes. Low return rates to low-acidified rivers further constrain enhancement and restoration programs. Hatchery smolt return rates to partially acidified rivers (mean annual pH 4.7 to 5.0) has declined to 0.05% at East River Sheet Harbour and to 0.03% at Liscomb River. Total salmon count at the Liscomb River fishway was only 25 salmon, and only 33 salmon were counted at East River Sheet Harbour. Tusket River smolt and adult assessment data indicated that the proportion of adult salmon counted in fishways while operating in the assessment mode for a portion of the season was 76.3%. An estimate of 12,408 wild smolts was derived for Tusket River. The high production rate of 48 smolts per escaped salmon indicated that perhaps only the higher pH Carleton River was the origin of the wild smolts. Forecasts to two index rivers indicated a 65% chance of attaining the conservation requirement above Morgans Falls and a 33% chance for St. Mary's River in 2000. Insert text here (justified-left)
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